Method and apparatus for forwarding label distribution protocol multicast traffic during fast reroute

Abstract

A computer apparatus comprising a processor and a forwarding engine arranged to forward LDP multicast traffic along a multicast tree having a primary and a backup path in a converged network topology, the processor being configured to cause the forwarding engine to forward traffic via the backup path upon a topology change and send a changed topology label and path vector to at least one neighbor node in the changed topology.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention generally relates to forwarding of multicast traffic. The invention relates more specifically to a method and apparatus for forwarding label distribution protocol multicast traffic along a multicast tree having a primary and a backup path.[0003]2. Background Information[0004]The approaches described in this section could be pursued, but are not necessarily approaches that have been previously conceived or pursued. Therefore, unless otherwise indicated herein, the approaches described in this section are not prior art to the claims in this application and are not admitted to be prior art by inclusion in this section.[0005]In computer networks such as the Internet, packets of data are sent from a source to a destination via a network of elements including links (communication paths such as telephone or optical lines) and nodes (for example, routers directing the packet along one or more of a pluralit...

AI Technical Summary

Problems solved by technology

Any such loops and any multicast network will propagate very quickly and can lead to network overload.

However, a problem inherent in both unicast and multicast traffic is that of micro looping.

However in the case of multicast networks there is the risk of exponential-traffic loops during convergence.

It will be seen that a similar transient micro loop problem can occur in the case of networks supporting multicast fast reroute as described in Raj et al.

However micro loops are not acceptable during fast reroute in view of the risk of data loss.

For example the problem can occur during fast reroute when a link-down event occurs, that is to say a link fails.

Also each node may take a different amount of time to compute and install the path independently.

Similar problems can arise when a new link is introduced in the network.

A further problem can arise when back up paths are invoked by multiple nodes.

This may occur, for example, upon node failure being detected by multiple repairing nodes across respective links.

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